液体火箭POGO振动缩聚模型研究

Aiming at the order of the propulsion system model being difficult to be reduced in liquid rockets' POGO model, a POGO reduced model method was proposed. The generalized inverse iterative method was used to do modal decomposition only for the transfer pipeline's finite element model to choose the any order modal equation of the transfer pipeline combined with other parts' equations to obtain the reduced model of the propulsion system. The POGO vibration reduced model was obtained by coupling the structure system's modal equations and the propulsion system reduced model. When the accumulator was taken as a pure flexible element or a non-pure flexible one, the dimension of the POGO vibration reduced model was composed of the transfer pipeline's modal variables, the structure's modal variables plus 1 or 2. The model's dimension was largely and the calculation examples showed that the POGO vibration reduced model has a high precision. Based on this reduced model, the effects of the accumulator's energy value and inertia of a certain liquid rocket on its POGO stability were studied. The results showed that for a pure flexible accumulator or a non-pure flexible one, its energy value and inertia have different and non-monotonic influences on the coupled model's stability at different time instants; when the structure system's frequency drops obviously due to the coupling effect, a reasonable adjustment of the accumulator's energy value or inertia can significantly increase the structure's coupled damping ratio to enhance the structure's stability.